1. Field of the Invention
The present invention relates to absorbent sanitary products and has been developed with particular attention paid to its possible application to absorbent sanitary products that can be worn like a pair of pants. A typical example of absorbent sanitary products of this type is represented by baby diapers or the like.
2. Description of the Related Art
For many years now, the solution adopted in a practically uniform way by all the manufacturers of the sector has been that of making these products in the form of elements shaped according to a general hourglass configuration, with a central body, in which there is provided a composite absorbent structure designed to absorb body fluids, and two end parts, a front one and a rear one, which extend laterally. The product is put on, bestowing on it a general U-shaped configuration and bringing the median stretch of the central body up to the area where the legs of the user are inserted. The end parts are extended around the waist of the user, connecting the mutually opposed side edges thereof together by means of adhesive labels or stickers, which can normally be re-positioned, or similar fastening elements in such a way as to be able to refasten the product around the body of the user.
These products have been traditionally manufactured and sold in the open condition, i.e., leaving to the person who applies the product the task of setting it around the body of the user and of fastening it according to a general pant-like conformation in the way referred to previously.
In the course of the last few years, there has emerged a renewed interest in diapers of the type commonly referred to as “training pants”. These are diapers of the type illustrated, for example, in the document U.S. Pat. No. 4,610,680, which are designed for being packaged and sold in a closed condition. When the product is taken out of the packaging, it has a conformation basically resembling that of a pair of pants. It is put on by making it slide over the legs of the user according to criteria basically similar to those followed for putting on a pair of pants. In view of the specific use to which the product is to be put, it is then envisaged that the product can be removed without having to slide it again over the legs of the user.
For this purpose, the product can be made in such a way as to be tearable (according to the criteria illustrated, precisely, in U.S. Pat. No. 4,610,680), or else by making the product so that it can be opened along the sides of the waist line, i.e., in an area of what may be defined the side flaps (as in the case of diapers of a traditional type, which are packaged and sold in the open condition), for example by envisaging the use of adhesive labels or stickers, sets of buttons, sets of press-studs or, according to a solution that has enjoyed a particular success, by envisaging the use of microhook fastening structures (also referred to as “Velcro fasteners”).
The use of such fastening elements must be reconciled with the need, to which reference has already been made previously, to have the training pant preferably produced and packaged in a closed condition, so as to enable it to be put on like a normal pair of pants.
Various patent documents deal with the problem of applying these fastening elements in the framework of an industrial cycle that can be implemented In a context compatible with the high production rates that are typical of the sector.
In this connection, reference may be made, for instance, to the documents U.S. Pat. Nos. 5,855,574, 6,210,388, 6,409,858, 6,477,628, and U.S. Pat. No. 6,461,344.
The above documents, which do not, however, exhaust the entire field on the subject, deal with the problem of the application of the aforesaid fastening elements by drawing particular attention to the functionality of the end product.
At least some of these documents of course take into account the need to make the corresponding products at typical industrial production rates. For this reason, they suggest, according to different modalities, resorting to production processes of a continuous type, in which the products are made starting from the individual component parts, operating preferentially on a continuous chain of products designed for being separated from one another, so as to arrive at the formation of the individual products only in the final stages of the process.
However, above all as regards the application of the aforesaid fastening elements, the solutions described in these prior documents do not take into account various problems that can assume a considerable importance both at the level of manufacture and at the level of use of the products in question.
In the first place, during fabrication of the sanitary product, in the process of apply a fastening element (or a part of said element) on a strip, web or chain, the aforesaid strip, web or chain moves along at a relatively high linear speed, and may expose the aforesaid element, when it is not completely anchored to the strip, web or chain on which it is applied, to flap or move. Movement of the strip during fabrication may cause the element itself to be positioned improperly for subsequent operations of treatment, in particular as regards possible operations of cutting.
Furthermore, it is necessary to take into account the fact that the cutting operation for separating the individual sanitary products or the type of connection of the side edges used, can lead to the formation of elements or surfaces of friction which, if not appropriately shielded, may give rise to even rather disagreeable drawbacks, for instance irritation or cutting of the skin, since they directly face the body of the user.
Furthermore, it is important to prevent the user (typically, for instance, a baby, perhaps even a very small baby) from possibly opening, with the application of even a modest force, the flaps set on the sides and causing undesirable release of the fastening element, in particular in the case of absorbent products designed to be refastenable.